Adaptive power control for multicast transmission

ABSTRACT

The power level of multicast data transmissions in a wireless communications network are controlled. Power level information is provided in a transmitted channel received by a user equipment. The user equipment measures the power level of a received signal. It compares the measured power level to the power level indicated by the power level information provided in the transmitted channel. Power level measurement information is included in a message sent by the user equipment depending on the results obtained when the power level measured by the user equipment is compared to the power level indicated by the power level information provided in the transmitted channel.

BACKGROUND

[0001] 1. Field of the Invention

[0002] The present invention is related to a method or apparatusproviding a multicast transmission in a communications network. Moreparticularly, the present invention is related to a method or apparatuscontrolling the power of a multicast transmission in a wirelesscommunications network.

[0003] 2. Discussion of the Related Art

[0004] 3GPP TS 23.041 V4.1.0 (2001-06) describes a Cell BroadcastService (CBS) for a wireless communications network according to thespecifications of the 3^(rd) Generation Partnership Project(www.3GPP.org) which is similar to Teletext service offered ontelevision, in that it permits a number of general messages to bebroadcast and received by all receivers within a particular region.These CBS messages are broadcast to defined geographical coverage areasalso called cell broadcast areas. A cell broadcast area may comprisesone or more cells, or may comprise the entire cellular network.Individual CBS messages are assigned their own cell broadcast area by amutual agreement between the information provider and the networkoperator. They may originate from a number of different Cell BroadcastEntities (CBEs), which are connected to a Cell Broadcast Center (CBC).CBS messages are then sent from the CBC to the cells via a radio accessnetwork in accordance with the CBS's coverage requirements.

[0005] CBS has the disadvantage that the messages are broadcastindiscriminately to all receivers within the geographical coverage area.It cannot identify different UEs for comprising a multicast group ormake evaluations between different cells (e.g., the number of UEs in acell, etc, etc.) or between different sessions (e.g. delay requirementsfor transmission, session priority, etc.)

[0006] 3GPP TS 22.146 V2.0.0 (2001-09) describes, at a high level, therequirements desired for an envisioned multicast service. Unlike CBS,the multicast service uses common network resources to provide datacommunications only to a restricted group of people in one or more cellsof the network who previously indicated their interest to receive themulticast service.

[0007] The intent is to enhance the current capabilities of theUniversal Terrestrial Radio Access Network (UTRAN) and the Core Network(CN) to make them become capable of providing the envisioned multicastservice. For example, the core network which knows only theLocation/Routing area level of the UEs of a plurality of servicesubscribers will forward the data to be multicast to the UTRAN. TheUTRAN, which knows the various cell locations of the UEs, in turntransmits the data to each of the UEs in a cell through one commonphysical channel on the radio interface. The transmissions of themulticast data in the various cells may be simultaneous or may bescheduled. Possible physical channels could be, for example, theSecondary Common Control Physical Channel (SCCPCH) which is currentlyused to transmit data of the transport channel and the Fast AccessChannel (FACH) which can transmit CBS data as well as other types ofdata.

[0008] The power level used for the transmission of a common physicalchannel (for example, open loop power control) is typically definedbased on cell structure and the conditions of the air interface (i.e.,as defined by the radio access network) without checking the conditionsin the cell from the UE point of view or the locations of the UEs. It istypically fixed and set high enough so that the UE furthest from thebase station and almost at the border of the cell is able to receive thetransmission. This has the disadvantage that the power level isunnecessarily high for most of the UEs. From the air interface point ofview, it also results in interference which could be avoided if theradio access network had information about authorised UEs in the cell.

[0009] Location information at least from URA (UTRAN Registration Area)level can usually only be fetched from a Radio Network Controller (RN C)if the authorized UEs and the UEs are in a Radio Resource Controller(RRC) connected state. However, it is more than likely that the most ofthe UEs are in IDLE mode and have no RRC connection. Therefore theirprecise location is unknown to the radio access network and the powerlevel of the multicast data transmission cannot be controlledaccordingly. In order to transmit the multicast data more efficiently,the radio access network should know the condition in the cell from theUE point of view and the locations of the authorized UEs, such aswhether there are any UEs in a cell upon activation of the multicastdata transmission, and adaptively control the power level accordinglybefore transmitting the data. Thus, there is a need for a system orapparatus for allowing the RNC to keep a record of the location of theUEs in the cells even though they are in the IDLE mode.

BRIEF SUMMARY

[0010] In the preferred embodiments of the invention, a radio accessnetwork defines the power level used for data transmissions in amulticast service based on information received from UEs authorized toreceive those multicast services. The UEs can be authorized, forexample, by the subscriber (i.e., an owner of a SubscriberIdentification Module card) making a service subscription in advancewith a service provider. Preferably, but not necessarily, thisinformation necessary for controlling the power level is providedwithout establishing any dedicated uplink feedback channels before orduring the transmission of the multicast data in a session. The powerlevel used can be less than the maximum level which would otherwise beused to transmit multicast data on one common physical channel.

[0011] One object of the preferred embodiments is to include radiointerference measurements in a UE when the UE is already active and touse such procedures between UE and the network, which are alreadyavailable for purposes other than power level control or which do notrequire any hard signalling exchange transactions in order to transmitrequired information from the UE to the network. The embodiments do notlimit the details of the measurements performed by the UE or the typesof signals or values produced by the measurements and calculations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a schematic block diagram indicating a networkarchitecture in which the preferred embodiments of the invention can beimplemented.

[0013]FIG. 2 illustrates a transaction performed when a UE enters a newcell according to a preferred embodiment of the invention.

[0014]FIG. 3 is a flow diagram indicating the operations performed whenthe UE enters a new cell according to a preferred embodiment of theinvention.

[0015]FIG. 4 illustrated the transactions performed for a UE when the UEmoves within a cell according to a preferred embodiment of theinvention.

[0016]FIG. 5 is a flow diagram indicating the operations performed foran UE when it is moving inside a cell according to a preferredembodiment of the invention.

[0017]FIG. 6 is an example of the register storing power levelinformation for UEs in a UTRAN according to a preferred embodiment ofthe invention.

[0018]FIG. 7 is an example of a CELL UPDATE message in a preferredembodiment of the invention.

[0019]FIG. 8 is an example of the URA UPDATE message in a preferredembodiment of the invention.

[0020]FIG. 9 illustrates the structure of a MULTICAST POWER INDICATIONmessage in a preferred embodiment of the invention.

[0021]FIG. 10 illustrates the UPLINK DIRECT TRANSFER message in apreferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The particulars shown herein are by way of example and forpurposes of illustrative discussion of the preferred embodiments of thepresent invention. The description taken with the drawings make itapparent to those skilled in the art how other various embodiments ofthe present invention may be embodied in practice.

[0023] Further, arrangements may be shown in block diagram form in orderto avoid obscuring the invention, and also in view of the fact thatspecifics with respect to implementation of such block diagramarrangements is highly dependent upon the platform within which thepresent invention is to be implemented, i.e., specifics should be wellwithin purview of one skilled in the art. Where specific details (e.g.,circuits, flowcharts) are set forth in order to describe exampleembodiments of the invention, it should be apparent to one skilled inthe art that the invention can be practiced without these specificdetails. Finally, it should be apparent that any combination ofhard-wired circuitry and software instructions can be used to implementembodiments of the present invention, i.e., the present invention is notlimited to any specific combination of hardware circuitry and softwareinstructions

[0024] Although the preferred embodiments of the present invention maybe described using an example system block diagram in a 3G wirelesscommunication network compatible or backward compatible with thespecifications promulgated by the 3^(rd) Generation Partnership Project,practice of the invention is not limited thereto, i.e., the inventionmay be able to be practiced with other types of wireless communicationnetworks, and in other types of environments.

[0025] Reference in the specification to “the preferred embodiment” or“an embodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. The appearances of thephrase “the preferred embodiment” in various places in the specificationare not necessarily all referring to the same embodiment.

[0026] The present invention is related to methods and systems forlocation registration and management of UEs in a UTRAN authorized toreceive a multicast service announcement in a cell where a networkcontinuously indicates the status of the multicast service situation tothe cell. This makes joining the multicast service much easier from a UEpoint of view. The present invention is also related to methods andsystems for a multicast service announcement in a cell where networksindicate when the network is about to start the next multicast sessionin order to allow UEs to wake up on the correct moment. User equipment(UE) according to the present invention may be a mobile network node(e.g., a mobile phone, Personal Data Assistant (PDA), or laptopcomputer) or non-mobile network node.

[0027] The preferred embodiments of the invention will be described withreference to the basic network architecture comprising a UTRAN 90 and aCN 100 shown in FIG. 1. First and second UE 11, 12 are connected via theUu radio interface to respective first node B 21 and second node B 22 ofUTRAN 90. First node B 21 and second node B 22 participate in the sameradio resource management and have the same function as a generic basestation. Furthermore, the UTRAN 90 comprises at least one Radio NetworkController (RNC) 30, which is connected to first node B 21 and secondnode B 22 via the lub interface and is responsible for the control ofthe radio resources in its domain, i.e. first node B 21 and second nodeB 22. RNC 30 is the service access point for all services the UTRAN 90provides to the CN 100.

[0028] CN 100 comprises a Mobile Switching CentreNisitor LocationRegister (MSC/VLR) 40 which is a switch (MSC) and database (VLR) thatconventionally serves an UE for circuit switched (CS) services. The MSCfunction is used to switch the CS transactions, and the VLR functionholds a copy of the visiting user's service profile, as well asinformation on the UE's location within the serving system. The part ofthe network which is accessed via the MSC/VLR 40 is often referred to asCS domain. The MSC/VLR 40 is connected to a Gateway MSC (GMSC) 50 whichis a switch at the point where the CN 100 is connected to external CSnetworks 110, e.g. Public Switched Telephone Networks (PSTNs),Integrated Services Digital Networks (ISDNS) or Public Land MobileNetworks (PLMNs). All incoming and outgoing CS connections go throughthe GMSC 50.

[0029] Furthermore, CN 100 comprises a Serving GPRS (General PacketRadio Services) Support Node (SGSN) 60 having a function similar to theMSC/VLR 40 but typically used for packet switched (PS) services. Thepart of the network accessed via the SGSN 60 is often referred to as thePS domain. The SGSN 60 is connected to a gateway GPRS Support Node(GGSN) 70 having a functionality similar to the GMSC 50 but for PSservices. The GGSN 70 is thus a switch at the point where the CN 100 isconnected to external PS networks 120, such as the Internet.

[0030] MSC/VLR 40 and the SGSN 60 are connected to the RNC 30 via theIu-interface which thus connects the UTRAN 90 to the CN 100. TheIu-interface is preferably an open standards interface which handlesswitching, routing and service control.

[0031] To achieve a multicast transmission function between the CN 100and the UTRAN 90 via the Iu-interface, different characteristics of themulticast related data transmission need to be taken into account notonly upon the active data transmission, but also upon reservation andconfiguration of the required resources from Iu-interface. For thesedifferent phases, 3GPP TS 25.331 V3.9.0 (2001-12) defines signalingprotocols such as RANAP (Radio Access Network Application Part) and IuUP(Iu Interface User Plane Protocol). RANAP is a signaling protocol in theIu-interface that contains all control information specified for theRadio Network Layer used for UTRAN-related issues. The IuUP also belongsto the Radio Network Layer and is independent of the CN domain that itis used for as much as possible. The purpose of the IuUP is to carryuser data related to Radio Access Bearers (RABs) over the Iu-interface.Each RAB has its own instance of the protocol. The protocol performseither a fully transparent operation, or framing for user data segmentsand some basic control signaling to be used for initialisation andonline control. Based on these cases, the luUP has two modes, i.e. atransparent mode for fully transparent operation and a support mode forpredefined SDU (Service Data Unit) sizes corresponding to framed userdata segments. Only upon the support mode, control procedures arespecified.

[0032] Thus, the Iu UP is the only protocol in the above group, which iscapable of transmitting not only control information but also user planedata (i.e. in this case multicast related data) and therefore it is acandidate for the user plane data transmission and the transmission ofconnection related control information over the Iu-interface. RANAP canbe used for transmission of control information and therefore they arenot directly available for multicast data transmission. The RANAPmessages can be used to configure and reserve resources from theIu-interface for the multicast session.

[0033] The operations which are performed in UE 11 or 12 according to apreferred embodiment of the invention are illustrated in FIGS. 2-5. Ingeneral, UE 11 or 12 receives system broadcast information (i.e., SIBsignalling messages) in the BCH transport channel mapped into a PrimaryCommon Control Physical Channel (PCCPCH) (301 in FIG. 3) in the cells ofa wireless communication network. When it enters a new cell as shown inFIG. 2 and 302 in FIG. 3, it generally performs any number of possiblearea update procedures (cell/URA/LA/RA/multicast, etc.). At this time,it checks the power level used for the multicast sessions in the cell.It does this by measuring the air interface based on information (e.g,the Eb/No, ELER, BER or other TPC value) in a received downlink channel(i.e., system broadcast information in the Broadcast Channel(BCH)/PCCPCH as shown in FIGS. 2 and 3, or SCCPCH which typicallycontains paging messages or FACH, etc.) These measurements and possiblecalculations produce a power level value. This power level value can becompared to the values received in SIB signalling messages. Depending onthe results obtained from the comparison, UE 11 or 12 may or may notsend an indication to UTRAN 90. For example, if the comparison indicatesthat the measured value is less than the values received in the SIBsignaling messages, then UE 11 or 12 may send an indication to UTRAN 90.(303 in FIG. 3)

[0034] Whether UE 11 or 12 sends a power level measurement indicationmay be based on any number or combination of factors in addition to thesimple logical comparison of the relative values described in theprevious paragraph. For example, it could depend on how small thedifference is between the measured value and power value received in theSIB signalling messages or whether the value exceeds the “absolutehighest power level” indicated in the SIB signalling messages. It coulddepend on the priorities of the multicast services which it is capableof receiving. It could also depend on the type of multicast service itis capable of receiving (e.g., a multicast service tied to a certainplace such as a mall or sports arena. There may be a plurality ofdifferent power level measurement indication types corresponding to thevarious combination of factors.

[0035] If UE 11 or 12 decides to send information on the measured powerlevel in order to control the power level, that information can beincluded and sent in a conventional message, such as a RRC Cell Updatemessage, a RRC URA Update message or a RRC LA Update message.Alternatively, the information may be included in a RRC Multicast AreaUpdate message or a RRC Multicast Power Indication message, as hereafterdescribed. (304 in FIG. 3) Preferably, UE 11 or 12 decides which messagetype is used. Also, if for some reason no update procedure is performedwhen UE 11 or 12 enters the new cell, UE 11 or 12 preferably decideswhether or not to send a message.

[0036] If UE 11 or 12 sends a message to UTRAN 90, the informationincluded in the message is put into a multicast register accordinglyalong with identifying information, such as Group ID, UE ID, etc (305 inFIG. 3). If information for UE 11 or 12 is already stored in themulticast register, then the register is updated with the newinformation. From this record, RNC 30 can check the starting power levelfor multicast data transmissions. It can also change the value of SIBsignalling if required.

[0037]FIGS. 4 and 5 show the operations performed when UE 11 or 12 movesinside a cell. If UE 11 or 12 is in idle mode, it preferably measuresthe power level from time to time to check the possibility of performingthe cell reselection procedure (502 in FIG. 5). At the same time, UE 11or 12 can also make measurements for power control purposes. Just asdescribed above with respect to FIGS. 2 and 3, the measurements can bebased on any downlink channel received by UE 11 or 12; the power levelvalue can be checked from information in the latest SIB messages andthis value can be compared to the measured value (503 in FIG. 5). If UE11 or 12 has moved to a place in the cell where the indicated powerlevel is not enough, it may send a RRC Multicast Power IndicationMessage as described below (504 in FIG. 5) to UTRNA 90. Preferably, UE11 or 12 can decide whether to send a message or not. The message can betransmitted on PRACH. Preferably, transmission of the message doesn'tcause the establishment of an RRC connection. The mode of the RLC layerin these circumstances should be the transparent mode and can uselogical channel CCCH.

[0038] If UE 11 or 12 sends a message to UTRAN 90, the informationincluded in the message is put into a multicast register accordinglyalong with identifying information, such as Group ID, UE ID, etc (505 inFIG. 5). If information for UE 11 or 12 is already stored in themulticast register, then the register is updated with the newinformation. From this record, RNC 30 can check the starting power levelfor multicast data transmissions. It can also change the value of SIBsignalling if required.

[0039] If UE 11 or 12 sees that the power level to be multicast on thecell is more than adequate for it, no power level information is sent toUTRAN 90. Also a relatively small difference between the received powerlevel information and measured power level can be handled so that noindication is sent to the UE.

[0040] UE 11 or 12 can check the power level periodically based on, forexample, timers supported in UE or IDLE mode measurement periods, etc.In general, it is desired that UE 11 or 12 is not unnecessarily shiftedfrom IDLE mode to make power level measurements, but instead makes themeasurements when it has other reasons to be active.

[0041] UTRAN 90 has to keep a record of the locations of the UEsauthorized to receive the multicast service. This location managementcan be carried out as described in U.S. Provisional Application No.60/332,506 filed on Nov. 26, 2001, the disclosure of which is herebyincorporated by reference in its entirety. As described above, whenUTRAN 90 receives power control information from UE 11 or 12, a recordof UE 11 or 12 is created in a multicast database if it was previouslyunknown in the database and is updated if it was previously known. Therecord of power control information associated with UE 11 or 12 in themulticast database is preferably deleted at the same time otherinformation associated with UE 11 or 12 is deleted from other databasesin UTRAN 90.

[0042] An example of a register containing power level information andUE location information in a multicast database is shown in FIG. 6. Ifthe power control information received from UE 11 or 12 indicate that achange of the power level (either increased or decreased) is warranted,UTRAN 90 can either the change the value in an SIB signalling message orwait until some predefined number of UEs also indicate the change(increase or decrease) in the power level. The method used to indicatepower level may affect this process of whether UTRAN 90 changes thevalue in a SIB signalling message or not.

[0043] UTRAN 90 preferably uses the power level indicated in SIBsignalling messages. If during an active session, RNC 30 gets anindication (as described below) that the UE 11 or 12 which requested thepower level has left the cell, then the power level can be decreased (ifdesired) during the active session with small steps. However, thisshould preferably be done until: 1) UTRAN 90 receives a new indicationfor the power level from one of the other authorised UEs in the cell(for this session); 2) the next highest power level is reached; or 3)the allowed number of power level reductions has been made for thesession. The power level may also be periodically decreased in smallsteps whenever there is an absence of power level measurementindications to ensure that the power level doesn't become higher thannecessary. The power level could become higher than necessary if, forexample, all UE's moved closer to cell center. These are just examples,and the RNC may also be set to decrease the power level in small stepsin other circumstances. If a multicast service is only for a specifiedplace, UTRAN 90 preferably shall use a fixed power level defined by anetwork and all UE based power level information shall be ignored.

[0044] As mentioned above, a new RRC Multicast Power Indication messagecan be used when UE 11 or 12 needs to transmit a new power levelindication to UTRAN 90. The UEs, which are in IDLE mode, cell_PCH andURA_PCH state can transmit such a message by using the PRACH physicalchannel, RACH transport channel and/or CCCH logical channel (i.e., theRLC mode used is transparent mode).

[0045] The UEs, which are in Cell_FACH state, can also send the RRCMulticast Power Indication message through PRACH/RACH by using DCCHlogical channel The timing of these messages can be varied as desired.For example, a restriction can be set so that a message is sent to UTRAN90 only once per measurement period.

[0046] The UEs, which are in Cell_DCH state, may or may not be allowedto send any power level indication to UTRAN 90 because UTRAN 90 can usepower level information which has already been defined for the dedicatedchannels.

[0047]FIGS. 7, 8 and 10 present examples of the modifications which maybe made to three currently existing RRC messages according to apreferred embodiment of the invention—the Cell Update message, the URAupdate message and the Uplink Direct Transfer message, respectively. Anexample of the structure which may be used for the new RRC MulticastPower Indication message is provided in FIG. 9. The references in thetables are to the numbered sections in 3GPP TS 25.331.

[0048] The SIB signalling messages preferably contain information fieldsfor at least the “highest power level” (based on UE measurements) andthe absolute highest power level accepted for a particular cell asdefined by UTRAN 90. The “highest power level” indicates the power levelcurrently defined for multicast sessions based on information receivedfrom authorised UEs. This field can be a binary field, in which case a“1” or “0” may be set to indicate that each multicast service, which issupported in a particular cell, is going to use the highest power levelon the radio interface. Alternatively, the value of this field can bebased on the number of multicast services (i.e., each multicast servicecould have a power level of its own); the priorities of the multicastservices; the number of multicast services which are linked with alocation+rest of the services or any combination thereof. (For example,football clips may have one value because the multicast service for itis available in a football stadium only and therefore the power levelcan be optimised based on the location of the football stadium.)

[0049] The second field for “absolute highest power level” indicates thepower level, which is defined by the network operator and follows thecondition of the air interface generally. The value in this field is theabsolute maximum value for the multicast data transmission and no newinformation from an UE can change the value. The value in this field inSIB message can based on the same principles described above for thefirst field.

[0050] As mentioned above, the user equipment may include power levelinformation in a Multicast Area Update message. This message is used totransmit multicast related information when the user equipment is inIDLE, Cell_PCH and URA_PCH state. The size of this message cannot exceedthe maximum size of one PRACH radio frame.

[0051] It is noted that the foregoing preferred embodiments have beenprovided merely for the purpose of explanation and are in no way to beconstrued as limiting of the present invention. While the presentinvention has been described with reference to preferred embodiments, itis understood that the words that have been used herein are words ofdescription and illustration, rather than words of limitation. Changesmay be made within the purview of the appended claims, as presentlystated and as amended, without departing from the scope and spirit ofthe present invention in its aspects. Although the present invention hasbeen described herein with reference to particular methods andembodiments, the present invention is not intended to be limited to theparticulars disclosed herein, rather, the present invention extends toall functionally equivalent structures, methods and uses, such as othertypes of wireless communication networks.

What is claimed is:
 1. A method of controlling the power level ofmulticast data transmissions in a wireless communications network,comprising: providing power level information in a transmitted channelreceived by a user equipment; measuring the power level of a signalreceived by said user equipment; comparing the power level measured bythe user equipment to the power level indicated by said power levelinformation provided in said transmitted channel; and including powerlevel measurement information in a message sent by said user equipmentdepending on the results obtained when the power level measured by saiduser equipment is compared to the power level indicated by said powerlevel information provided in said transmitted channel.
 2. A methodaccording to claim 1, wherein the method is carried out when the userequipment enters a new cell.
 3. A method according to claim 1, whereinsaid comparing step is performed in said user equipment and said powerlevel measurement information is included in said message sent by saiduser equipment if the power level measured by said user equipment isless than the power level indicated by said power level informationprovided in said transmitted channel.
 4. A method according to claim 3,wherein the message sent by said user equipment if the power levelmeasured by said user equipment is less than the power level indicatedby said power level information provided in said transmitted channel isa Cell Update message.
 5. A method according to claim 3, wherein themessage sent by said user equipment if the power level measured by saiduser equipment is less than the power level indicated by said powerlevel information provided in said transmitted channel is a URA Updatemessage.
 6. A method according to claim 3, wherein the message sent bysaid user equipment if the power level measured by said user equipmentis less than the power level indicated by said power level informationprovided in said transmitted channel is an Uplink Direct Transfermessage. 7 . A method according to claim 3, wherein the message sent bysaid user equipment if the power level measured by said user equipmentis less than the power level indicated by said power level informationprovided in said transmitted channel is an Multicast Power Indicationmessage.
 8. A method according to claim 3, wherein said user equipmentdecides what type of message to send if the power level measured by saiduser equipment is less than the power level indicated by said powerlevel information provided in said transmitted channel.
 9. A methodaccording to claim 1, wherein the method is performed periodically whilesaid user equipment is in the same cell.
 10. A method according to claim1, further comprising storing in a multicast database said power levelmeasurement information included in said message sent by said userequipment.
 11. A method according to claim 1, wherein said message sentby said user equipment does not cause the establishment of an RRCconnection. 12 A method according to claim 1, wherein said wirelesscommunication network changes the power level of multicast datatransmissions based on the power level measurement information includedin a message sent by said user equipment.
 13. A method according toclaim 12, wherein the power level of said multicast data transmissionsis less than the maximum power level required for all user equipments inthe wireless communication network.
 14. A method according to claim 12,further comprising tracking the location of user equipments in thewireless communication network.
 15. A user equipment for receivingmulticast data transmissions in a wireless communications network, saiduser equipment adapted to carry out a power level control methodcomprising: receiving power level information in a transmitted channel;measuring the power level of a received signal; comparing the measuredpower level to the power level indicated by said power level informationprovided in said transmitted channel; and including power levelmeasurement information in a message depending on the results obtainedwhen the power level measured by said user equipment is compared to thepower level indicated by said power level information provided in saidtransmitted channel.
 16. A user equipment according to claim 15, whereinthe method is carried out when the user equipment enters a new cell. 17.A user equipment according to claim 15, wherein the message sent by saiduser equipment is a Cell Update message.
 18. A user equipment accordingto claim 15, wherein the message sent by said user equipment is a URAUpdate message.
 19. A user equipment according to claim 15, wherein themessage sent by said user equipment is an Uplink Direct Transfermessage.
 20. A user equipment according to claim 15, wherein the messagesent by said user equipment is an Multicast Power Indication message.21. A user equipment according to claim 15, wherein said user equipmentdecides what type of message to send if the measured power level is lessthan the power level indicated by said power level information providedin said transmitted channel.
 22. A user equipment according to claim 15,wherein the method is performed periodically while said user equipmentis in the same cell.
 23. A network element in a wireless communicationnetwork, said network element performing a method comprising: providingpower level information in a downlink channel transmitted to userequipment in said wireless communication network; receiving a messagefrom user equipment, said message including power level measurementinformation indicating the results of a comparison of the power levelmeasured by said user equipment to the power level indicated by saidpower level information provided in said transmitted channel; andcontrolling the power level of multicast data transmissions based onsaid message.
 24. A network element according to claim 23, wherein saidwireless communication network changes the power level of multicast datatransmissions based on the power level measurement information includedin a plurality of messages sent by a plurality of user equipment.
 25. Anetwork element according to claim 23, wherein the power level of saidmulticast data transmissions is less than the maximum power levelrequired for all user equipments in the wireless communication network.26. A network element according to claim 23, further comprising trackingthe location of user equipments in the wireless communication network.27. A network element according to claim 23, wherein said networkelement stores the power level measurement information included in aplurality of messages sent by a plurality of user equipment in amulticast database.
 28. A network element according to claim 24, whereinsaid network element is adapted to receive a messages including powerlevel measurement information indicating that the power level measuredby said user equipment is less than the power level indicated by saidpower level information provided in said transmitted channel and toprovide that said wireless communications network increases the powerlevel of multicast data transmissions in response to said messagesincluding said power level measurement information.
 29. A networkelement according to claim 24, wherein said network element is adaptedto receive messages including power level measurement informationindicating that the power level measured by said user equipment is lessthan the power level indicated by said power level information providedin said transmitted channel and to provide that said wirelesscommunications network decreases the power level of multicast datatransmissions in the absence of said messages.